Definitions of authority
(also: precedent) an important judicial decision or accepted source of information that can be used to help support a case
Mr Popkins referred to a number of respected authorities during his legal arguments.
a body with administrative powers and the legal power to enforce the law; a group of people with official responsibility for something
The Park Authority is responsible for maintaining the national parks.
the official or legal power given to a person or an institution to do something
The agent had no authority to take out a loan on behalf of the company.